单自由度体系弹塑性反应谱研究及在桥梁工程中的应用

发布时间：2018-12-11 06:49

【摘要】：反应谱设计是结构抗震设计中的一种重要方法,反应谱法具有计算简单,且标准设计谱生成只需计算一次,适用性强的优点的。然目前国内的抗震设计规范中普遍采用弹性反应谱理论,通过地震力调整系数进行折减,从而计算结构弹塑性响应。此过程中并未考虑地震波自身的频谱特性及特征周期对地震力调整系数的影响,使结果增大了误差的可能性。本文通过反应谱计算软件Bispec,对理想弹塑性模型、硬化指数?=0.10的双折线滞回模型及Clough刚度退化模型三种模型的单自由度体系进行了在地震作用下动力弹塑性分析,同时考虑延性、阻尼、后期刚度、二阶效应及场地等因素的影响。通过特征周期gT对横坐标的标准化,即横坐标为/=0~10gT T,延性变化范围2~8,统计得到在A、B两类场地条件下的R?谱,并从中发掘延性、阻尼、后期刚度、二阶效应对R?谱谱值的影响规律。主要研究成果有:(1)统计后三种模型在A、B两类场地条件下的Rμ谱在特征周期Tg附近存在相当明显的峰值特征,场地条件的不同,其Rμ谱存在一定的差异,但总体趋势相近,T/Tg=2可作一分界点,此后谱曲线基本趋于一直线,随延性的增大,Rμ谱谱值有所增加,各延性下的谱曲线特征基本一致。(2)Rμ谱值随阻尼比的增大而减小,对峰值的影响尤为显著。当阻尼比达到0.15时,Rμ谱峰值逐渐消散,在不同延性条件下,阻尼对Rμ谱的影响趋势大体一致;在同一延性条件下,随阻尼比的增大,Rμ谱谱值减小,且谱曲线随阻尼的增大而受其影响的程度逐渐降低,说明阻尼的影响存在一定的范围。(3)在同一延性条件下,随后期刚度的增大,等延性强度需求谱谱值逐渐增大,最终后期刚度对谱曲线的影响逐渐趋于一稳定水平。(4)在同延性条件下,随二阶效应系数?的增大,Rμ谱谱值逐渐降低,且其降低趋势亦在增大,较大的P??效应不利于结构的稳定;在??0.08时,延性对不同?下的Rμ谱的影响程度不是很大,??0.08时,其区别显现出来,随延性的增大,影响程度递增,在确定的?值下,其对谱曲线的影响随周期的增大最终处于一常水平。(5)对单柱结构弹塑性响应,通过Vindic模型、本文模型及时程分析,采用Chopra的改进能力谱法得到了比较准确的计算结果,体现出Chopra的改进能力谱法对于计算桥梁结构弹塑性反应是一种可行的方法,同时也说明本文直线段模型亦是可行的。
[Abstract]:Response spectrum design is an important method in seismic design of structures. The response spectrum method has the advantages of simple calculation and only need to be calculated once to generate standard design spectrum. However, at present, the elastic response spectrum theory is widely used in the domestic seismic design code, and the seismic force adjustment coefficient is reduced to calculate the elastoplastic response of the structure. In this process, the influence of the frequency spectrum characteristics of the seismic wave and the characteristic period on the seismic force adjustment coefficient is not considered, which increases the possibility of the error. In this paper, the single degree of freedom (DOF) system of ideal elastoplastic model, double fold hysteretic model with hardening exponent = 0.10 and Clough stiffness degradation model is analyzed by response spectrum calculation software Bispec,. At the same time, the effects of ductility, damping, late stiffness, second order effect and site are considered. In this paper, the characteristic periodic gT is used to standardize the horizontal coordinates, that is, the transverse coordinate is / = 0~10gT T, and the ductility range is 2 ~ 8. Spectrum, and explore the ductility, damping, late stiffness, second-order effects on R? The influence law of spectral value. The main research results are as follows: (1) the R 渭 spectrum of the last three models has obvious peak value near the characteristic period Tg under the condition of two kinds of sites, and the R 渭 spectrum of the three models is different with the difference of the site conditions. But the general trend is similar, T/Tg=2 can be used as a dividing point, after that, the spectral curve tends to be a straight line, and with the increase of ductility, the value of R 渭 spectrum increases. (2) the value of R 渭 decreases with the increase of damping ratio, especially the effect of peak value. When the damping ratio reaches 0.15, the peak value of R 渭 spectrum dissipates gradually, and the effect of damping on R 渭 spectrum is almost the same under different ductility conditions. Under the same ductility condition, with the increase of damping ratio, the spectral value of R 渭 decreases, and the spectral curve decreases gradually with the increase of damping, which indicates that the influence of damping exists in a certain range. (3) under the same ductility condition, With the increase of stiffness in the following period, the required spectral value of isoductive strength gradually increases, and the effect of stiffness on the spectral curve gradually tends to a stable level in the later stage. (4) under the same ductility condition, with the second order effect coefficient? The value of R 渭 spectrum decreases gradually, and the decreasing trend is also increasing. The effect is not conducive to the stability of the structure, and at 0.08, the ductility is different. The influence of the R 渭 spectrum is not very great, when? 0.08, the difference appears, with the increase of ductility, the degree of influence increases. (5) for the elastoplastic response of a single column structure, the time-history analysis of this model is based on the Vindic model. The improved capability spectrum method of Chopra is used to obtain more accurate calculation results, which shows that the improved capability spectrum method of Chopra is a feasible method for calculating the elastoplastic response of bridge structures, and it also shows that the linear segment model in this paper is feasible.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U442.55

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